Attempts have been made to provide ventilating systems which prevent heat loss through the ventilator aperture during the colder months of the year.
One such device is disclosed in U.S. Pat. No. 4,231,288. This device includes a disk-like member which is placed over the ventilator aperture. This disk member is held in place by a mechanical member which extends between and is connected to the ventilator and the disk-like member. Another roof ventilating system having a disk-like member is disclosed in U.S. Pat. No. 1,601,191. In this device the disk-like member is threadedly mounted on the aperture for opening and closing when desired.
Another device is disclosed in U.S. Pat. No. 4,287,816. This device includes a separate enclosure designed to be mounted around the ventilator itself during the winter months.
Still other ventilator systems such as for example as is disclosed in U.S. Pat. No. 925,252 discloses a damper like closing member sitting in the aperture which can be opened and closed by a cable when desired.